Photosynthate transfer through a common mycorrhizal network
Photosynthate transfer from an autotrophic orchid to conspecific heterotrophic protocorms through a common mycorrhizal network
Does the ‘wood wide web really exist? Can speculation that parental plants nurture their young be justified? New research by a group including Katie J Fields at the University of Shefield in the UK has shown a definite transfer of carbon in the form of photosynthate essential for protocorm development.
The researchers have shown a definite carbon transfer from ‘adult’ Dactylorhiza fuchsii or common spotted orchid to seedlings via an associated mycorrhizal network. These ground dwelling orchids are typically difficult to propagate without a mycelial network, in this case Ceratobasidium cornigerum was used. Using a growth medium including powdered oats and a dash of pineapple juice, they arranged protocorms around an orchid plantlet 3-4 cm tall. They also introduced the symbiotic fungus that grew outwards from the green plant forming a dense interconnected mycelial network connecting the protocorms with the photosynthetic green-leaved plant.
The surface of the growth medium was sealed, separated from the atmosphere surrounding the plant. Carbon dioxide containing carbon-14, an isotope of carbon, was introduced into the chamber containing the green plant allowing the researchers to measure the transfer of carbon from the atmosphere surrounding the green plant to the protocorms.
They found measurable quantities of the carbon in the fungal mycelium and significant quantities in the protocorms. These findings, they concluded, provided the physiological underpinning necessary to explain the occurrence of parental nurture by intergenerational orchid mycorrhizal connection.
For terrestrial orchid species that show aggregated distributions clumped around established adults, the researchers suggested that carbon transfer via common mycorrhizal networks may be of fundamental importance and thus have a role in orchid conservation and management. Species such as Cypripedium calceolus, which are rare, have very specific Tulasnella mycorrhizal symbionts and might benefit from the use of transplanted ‘nurse plants’ to facilitate regeneration from seed. For more information: